
Class TS ^\OQ 

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COPYRIGHT DEPOSnV 



The Practical Enameler 

WITH ESPECIAL REFERENCE TO 

ENAMELING SHEET-STEEL 
AND CAST-IRON WARE 

With Useful Information Relating to All Side Lines 



AN EXCEPTIONALLY COMPLETE 



Manual for Self -Instruction 



FOR ALL THOSE ENGAGED OR 
INTERESTED IN THE TRADE 



OTTO GRAMPP 

AUTHOR and' publisher 
New York, U. S. A. 

1909 






C-Ci. A 368238 



PREFACE 

The author of this volume has assumed the 
task of supplying the Enameling Trade with a 
really useful and readily understood Manual, 
treating the subject in an absolutely tip-to-date 
manner, and availing himself of the latest 
achievements of modern scientific progress. 

As the Enameling Trade up to the present 
time has not had any literature worth mention- 
ing, in the English language, at least, I feel con- 
fident that my efforts, devoted to so useful a 
cause, will meet with general appreciation. 

The Author. 



Table of Contents 



Page 

A General Review 7 

Male and Female Labor 12 

Danger of Injury to Employees 14 

Wages and Working Hours 16 

Annealing and Pickling the Crude Ware 20 

The Crude Materials Entering Into the Composition of 
Enamel Fluxes 24 

The Smelting Process 55 

The Grinding Process 58 

The Coating and Firing Processes 62 

The Coefficients of Expansion of Sheet-steel Formulas 70 

Cast-iron Enameling 72 

Majolica Ware Enamels 75 

Enamel Painting 78 

Pastel Painting on Enameled Paints 83 

Pastel Crayons 85 

The Application of Photo-ceramics to Enamel 87 



INTRODUCTION 

After many years of technical work in the 
EnameHng Trade, during which time I had oc- 
casion to acquire an extensive and thorough 
knowledge of the various enameling methods, I 
have decided to embody in this volume the results 
of my experience for the benefit of those engaged 
and interested in the trade, giving at the same 
time a number of reliable and practical receipts 
for the preparation of enamels. 

I have also devoted a chapter to a briefly out- 
lined description of the technique of enamel 
painting which may prove of interest, not only 
from a business standpoint, but also for the 
lovers of art. 

It appeared to me advisable to refrain, as much 
as possible, from the use of scientific or technical 
terms, thereby presenting to my readers a lucid, 
readily comprehensible review of the subject 
matter. 

I therefore cherish the hope that the volume 
I herewith submit to them may prove a reliable, 
useful and profitable guide for all who are inter- 
ested in this branch of industry and art. 

New York, 1909. Otto Grampp. 



A General Review 

Enameling is numbered among the very an- 
cient arts, the Egyptians, Greeks and Etruscans 
having been exceedingly skilful in the produc- 
tion of enameled articles. 

In the loth century, Theophilus, a monk, wrote 
a detailed description of the preparation of 
enamel. 

Subsequently, in the latter part of the Middle 
Ages, the Italians were the first to produce trans- 
parent enamels which enabled the French to 
evolve the art of enamel painting, a discovery 
which was chiefly utilized on a trade basis in the 
French city of Limoges. 

The civilized nations of Eastern Asia were 
also at an early date conversant with the enamel- 
ing art. 

However, as enameled articles in those times 
were exceedingly valuable, in view of the ex- 
pensive method of production, they could only 
be purchased by the wealthy, who acquired them 
as a luxury, the making of enameled articles on 



a large scale consequently being wholly out of 
the question. 

The first production of enameled ware for 
practical purposes does not date back further than 
the 19th century, previous to which time clay, 
stone, woodenware, etc., were found in every 
household. As vessels of this description were 
not, however, available for all purposes, it soon 
became necessary to provide such as could be 
readily cleaned and used for every purpose, 
while being at the same time proof against all 
chemical action, and free from any qualities 
which might make them injurious to health. A 
further important requirement was cheapness, 
bringing these utensils within the reach of the 
poor. 

The enormous technical progress which marked 
the latter half of the i8th century made it pos- 
sible to produce vessels complying with the afore- 
said requirements. These utensils were, in fact, 
the forerunners of modern enameled sheet-iron 
ware which, however, was not produced on a 
manufacturing scale until Enameling Works 
were established in Germany in the early fifties 
of the last century. During the past 25 years 
the development of this new branch of industry, 
which has wholly superseded the old art enamel, 

8 



has been rapid, until it has reached its present 
importance. The production of enamel cooking- 
utensils, therefore, cannot be considered a new 
invention, but only an improved application of a 
process known long ago. 

Like all innovations, enameled ware was at 
first received with many misgivings. These uten- 
sils were looked upon with distrust, and they 
were not thought to be durable, because they were 
too light in weight. They were also considered 
injurious to health. 

The medical fraternity spread reports in which 
the assertion was made that the accidental swal- 
lowing of enamel chips was frequently the cause 
of inflammation of the blind gut. After having 
been denied by various authorities, this conten- 
tion was recently again disproven by professors 
on the medical staff of one of the largest and 
best-known hospitals of Hamburg (Germany). 
I shall have occasion to note their opinion in one 
of the following chapters of this volume. 

In view of this opposition it was at first a 
rather difficult matter to find a market for enam- 
eled ware, until the public began to gradually rec- 
ognize the many advantages afforded by these 
utensils, whose popularity increased until at the 
present time it would be a difficult matter to find 



a household not equipped with an assortment of 
enameled sheet-iron ware. 

In addition to enameled sheet-iron ware, enam- 
eled cast-iron kitchen utensils, etc., w^ere placed 
upon the market and bought principally by people 
who feared that their health might be impaired 
by the use of enameled tinware. These cast-iron 
utensils, however, are only rarely met with at 
present, as they have almost completely made way 
for the light, convenient enameled sheet-steel 
ware. 

The following figiu*es will give an idea of the 
rapid development of the enameling industry: A 
certain manufacturing concern employed 260 
hands in 1872, 453 in 1881, 788 in 1884, 1,300 in 
1887, 1,832 in 1890 and 3,600 hands in 1900. 

Various reasons make it impossible to give a 
detailed and accurate review of the labor condi- 
tions prevailing in the enameled sheet-steel ware 
industry considered as a whole. 

The very great diilerence in the assortments 
made, and in the technical installation and ar- 
rangement of the various plants, precludes the 
possibility of finding even two shops in which 
the hands are worked under the same system. 

Comparisons between the various manufactur- 
ing plants in regard to the wage scale, living ex- 

10 



penses and rents are likewise impracticable, in 
view of the fact that these figures are largely 
determined by local conditions, while the manu- 
facturing plants are distributed over a number 
of different countries. 

The personal views of manufacturers re- 
garding the required number of working hours, 
the manner in which the work should be divided 
and other important questions are, moreover, 
so widely divergent that any attempt to obtain 
uniformity regarding these matters would result 
in absolute failure. 

The one feature common to all enameling 
plants is a system by which the work is most 
thoroughly specialized or divided among the 
hands, this being, in fact, the only means by 
which manufacturers can produce an enormous 
output of enameled ware with a limited number 
of hands. 



11 



Male and Female Labor 

Enameling Works employ both men and 
women, the work being divided among them 
according to the judgment of the management. 
As a general rule, how^ever, I may state that men 
only are employed for making the enamel com- 
position and the packing cases, and that the 
machinery is also exclusively operated by men. 

Both men and women work in the pickling 
rooms, where the women are more especially em- 
ployed for scrubbing the goods, as well as in the 
enameling shop and in the stockrooms. 

The coating of the utensils with enamel com- 
position, the rimming, drying and annealing, as 
well as the sorting of the various grades and the 
packing of the goods, are done by both men and 
women. 

Women are particularly well adapted for light 
work requiring a certain deftness and skill with 
the fingers, while men are, of course, better 
equipped for all kinds of work requiring physical 
strength. Experience, furthermore, has proven 

12 



that it is more advisable to employ men than 
women for all such work as might prove danger- 
ous to a careless person. This applies more 
especially to the stamping work. 



13 



Danger of Injury to 
Employees 

There being, as a rule, only very slight danger 
of injury to persons employed in enameling 
works, the number of accidents is by no means 
large. The stamping shop is, in fact, the only 
one in which very careless hands can suffer seri- 
ous injury, although the dies move so slowly that 
accidents are infrequent. Moreover, the danger 
of having their fingers pinched off is so apparent, 
and is so constantly before the workmen, that it 
makes them doubly careful. 

In an attempt to make the operating of stamp- 
ing machinery absolutely free from danger, one 
of the largest works in Germany has offered to 
pay a considerable sum of money to any one in- 
venting a safety device which would make it im- 
possible for the fingers or hands of the operator 
to be caught in the machine. The problem, how- 
ever, has not as yet been solved. 

The only work which might in course of time 

14 



prove injurious to the health of the employees is 
the mixing of the enamel compositions. The 
men should, therefore, never neglect to use the 
safety device which protects them from inhaling 
through their mouths and nostrils the dust pro- 
duced during the mixing process. 



15 



Wages and Working Hours 

The various Enameling Works pay their hands 
either by the hour, for individual piece work, or 
for piece work by gangs or crews. 

Hands operating power machinery are always 
paid by the hour. All work in which accuracy 
and a perfect product are of greater importance 
than speed should, moreover, also be paid for per 
hour. This applies more especially to the mixing 
of the enamel compositions. In some shops the 
firing and annealing are paid for by the hour, and 
in others by the piece. The wages for all me- 
chanical work, such as stamping, spinning, cut- 
ting, folding, packing, etc., are exclusively fig- 
ured on a piece-work basis, the wage scale for 
such piece-work being, of course, determined by 
the management of the individual shops. 

Although manufacturers hold widely divergent 
opinions regarding the advantages or disadvan- 
tages of the piece-work system, it is an incontro- 
vertible fact that it greatly facilitates supervision 
in the shops. 

16 



In order to ascertain the relative influence of 
improvements introduced in the installation of 
new manufacturing plants, or of modifications in 
the machinery of existing plants, the old wage 
scale for piece-work should be maintained for 
some time, when the increase in the earnings of 
the individual hands will show to what extent the 
output has been increased by such improvements 
or modifications. 

In case an invention made by one of the hands 
proves a success, the inventor should receive an 
adequate reward, inasmuch as the chance of being 
thus remunerated will induce many of the men to 
acquire a more thorough knowledge of the ma- 
chines they operate, thereby possibly discovering 
chances of practical improvements which cannot 
fail to prove profitable to their employer. 

Ten hours constitute the average working day 
in Enameling Works. The men in charge of fir- 
ing the goods frequently work in eight-hour 
shifts, in order to utilize to better advantage the 
furnaces in which the fire must, of course, be 
constantly kept up, whether they are being used 
or not. 

In consequence of the dififerent operating sys- 
tems it would be impossible to establish any gen- 

17 



eral rule ii^oveniing the number and division of 
the working hours in EnanieHng- Works. 

In view of the fact that the consumption of 
enameled cooking- utensils has constantly in- 
creased din"ing' the last ijuarter of a century, and 
that many new markets have been opened up. 
with the result that the annual output has at- 
tained enormous proportions, it is indeed surpris- 
ing that the nimiber of Enameling Works in the 
United States, pre-eminently a land of progress. 
has remained extremely limited, a fact which is 
all the more inexplicable because a large percent- 
age of her annual consumption of enameled ware 
is imported from Germany and Austria, although 
the import duty on enameled cooking utensils is 
40 per cent, ad \'alorem, figured on the value of 
the giHuls ill the country of origin. 

In 1904 the number of Enameling Works es- 
tablished in Germany was seventy-one, with a 
total working capital of from 50,000,000 to 
LXD,ooo.ooo marks, and employing about 22,000 
hands. The annual sales of some of these works 
range between 8,000,000 and 0,000.000 marks. 

These figures demonstrate that the manufac- 
ture of enameled ware has become an exceed- 
ingiv important factor in industrial economics, 
and that only unceasing etYort. continual progress 

IS 



and inipro\'ed, up-to-date operating methods can 
insure an adequate development of this industry 
in our country, and place it in a position to suc- 
cessfully meet the competition of foreign goods. 



19 



Annealing and Pickling the 
Crude Ware 

The proper preparation ot" the crude ware he- 
tore it goes to tlie enameling rooms is one of the 
most important l"eatures of the enameHng proc- 
ess, and should accordingly receive most careful 
attention. 

We shall tirst {proceed to consider the anneal- 
ing process. The nuil'tle furnace used iov anneal- 
ing should he kept at a constam heat oi ahiuU 
800 degrees V.. as the product would sulYer to the 
same extent either hv heing alUnved to remain 
too long in an underheated furnace, or hv heing 
annealed t(X^ rapidly hy exposure to excessive 
heat. 

In order to insure perfect annealing, the crude 
ware, before being charged into the annealing 
furnace, is lirst dipped in a weak mixture of 
water and muriatic acid, for the purpose of hav- 
ing all grease and impurities adhering to the 
ware (in consequence o\ its having passed 

20 



througli tlic stainiHiig- ])rcsscs and i)lanisliing' 
machines) c(>iiij)lctcly consumed durinj^ Uic 
annealing- process. 

Tlie crude ware should not under any circunr 
stances he jjiled uj) too hij^Ii, or nested in the an 
neahng furnace, and unless strict attention is paid 
to liiis re(|uirenient, the surfaces will not come in 
contact with a sufficient volume of oxyj^en, and 
the oxidation will conscciuently he uneven, a 
defect which results in the formation oi un- 
sightly hlisters, and therefore increases io a 
very considerahle extent the percentage of sec- 
onds and waste. 

After the crude ware has heen prepared as 
ahove descrihed it is removed to the pickling 
room. The pickle, which may he composed either 
of 90 parts water and 10 parts C(;ncentrated sul- 
phuric acid of 65' Ik', or of one part muriatic 
acid and two parts water, must be mixed in vats 
especially made for that purpose of pitch pine, 4" 
thick, with groove and tongue joints, and 
thoroughly coated with tar on the outside. 

Muriatic acid pickling liquors are preferable 
to thr>se made with sulphuric acid; first, because 
they are cheaper, and, secondly, because they irri- 
tate the lungs of the workmen to a lesser extent. 
The weight of the pickle in each vat should be 

21 



ascertained daily, this being an operation which 
an intelHgent workman can easily accomplish in 
a few minutes. 

After immersing the crude ware in the pickle, 
and leaving it in the same until sufficiently 
pickled, a process to which any wcM^kman can at- 
tend after a short training, it is taken out and 
placed in a vat of pure water, in which it is left 
for an hour at least, to make sure that all of the 
acid has been washed off. The crude ware is 
then scoured with sand and boiled for a few min- 
utes in weak soda lye. After having been boiled 
it is dried and immedialely conveyed to the 
enameling room. 

It is not advisable to allow pickled crude ware 
to stand overnight, and all the goods should, in 
fact, be coated with enamel on the same day they 
are pickled. 

When the pickling vats have been used for a 
short time, a nuiddy mass composed of precipi- 
tated oxide of iron and iron scale is deposited on 
the bottom. This deposit must at certain inter- 
vals be removed from the vats. For this purpose 
the clear acid solution is drawn off into clean old 
barrels, the bottom o\ the vats is cleaned, the 
acid which has boon drawn off poured back, and 
fresh water and pure acid added, uiuil the acid 



bath has recovered its standard strength. The 
old acid soUition must always be used again, not 
only because it means a very considerable sav- 
ing, but also because a bath made without acid 
that has previously been used acts very slowly 
and imparts a bluish-gray color to the pickled 
ware. 

Before coating the goods with enamel, they 
must be examined to ascertain whether the folded 
seams are tight, and whether the ware has been 
closely riveted. This inspection can be made by 
the same workman charged with removing the 
dents from the utensils. If the folded seams and 
the rivets are not tight, and also when the rims 
are poorly bordered, blisters will form, and it be- 
comes consequently impossible to produce neatly 
finished and perfect ware. 

The various defects found in finished enameled 
ware will be discussed in one of the following 
chapters. 



23 



The Crude Materials Enter- 
ing Into the Composition 
of Enamel Fluxes 

BORAX. 

Borax (Na2 B4 O? + 10 H2 O), known in chem- 
istry as Sodium Borate, is readily soluble in hot 
water. It melts at red heat and loses 47% of 
crystallization water in the melting process. This 
salt is used in all Enameling Works as the most 
effective flux, best adapted for this special pur- 
pose. During the melting down of the Enamel, 
Borax shows a peculiar action, inasmuch as it at 
once and directly induces the formation of the 
ground-mass. 

Natural Borax is found on the coast of Cali- 
fornia and in other localities, but it is likewise 
obtained by neutralizing boracic acid (HsBO.O 
with sodium carbonate. 

Manufacturers will find it to their advantage 

24 



to calcine and melt a small sample of each ship- 
ment of Borax they receive, as this will enable 
them to ascertain at once whether the Borax con- 
tains any oxide that would color the Enamel. 
When smelted, pure Borax should present the 
appearance of pure crystal glass, while a green 
coloring indicates the presence of copper, a red 
coloring the presence of peroxide of iron (Fe2 Os) 
and a purple coloring the presence of manganese 
compounds. 

Borax should always be bought either ground 
fine, or in the form of very small crystals, be- 
cause it will mix better with the other component 
parts of the Enamel and fuse more perfectly with 
the same, thereby producing a finer and more 
uniform glazing. 

When heated in the blowpipe flame Borax un- 
dergoes the same changes as boracic acid. At 
first the mass bubbles up violently, and thereupon 
quickly melts down until it assumes the appear- 
ance of a glass bead. If powdered Borax is 
mixed with metal oxide and the mixture smelted, 
the oxide will dissolve completely in the Borax. 
When mixed w4th the oxides of iron and anti- 
mony (H2O3) the bead will be yellowish red, 
while an admixture of cupric (Cu O) or chromic 
oxide (Cr- O3) will produce a red, cobaltic oxide 

25 



(C02O3) a blue, and manganese dioxide (Mn 
O:.') and oxide of manganese (MnsO*) a brown 
bead. 

Borax should always be stored in an absolutely 
dry place, because it is strongly hygroscopic (i. e., 
it absorbs the moisture from the air) and will 
consequently contain a large additional amount 
of water of crystallization after having been 
stored in a humid place, a circumstance which 
may in some cases prove a serious disadvantage 
in the preparation of enamel fluxes. 

A mixture of boracic acid and soda (made by 
the ammonium process) in the chemically correct 
proportions may be used instead of Borax. 

Borax and boracic acid are used in the prepara- 
tion of glazing for earthenware and fine crockery 
in a similar manner as in the enameling industry, 
for glass and china, and of optical glasses. The 
use of Borax for welding metals, soldering (so 
called "Jewelers' Borax"), etc., is undoubtedly 
known to my readers. The welding of cast steel, 
for instance, was for a long time considered im- 
possible, until it was finally discovered that it 
could be welded by using a flux containing a com- 
paratively large percentage of boracic acid or 
Borax. The composition known as "Kohler's 
Cast Steel Flux" contains 8 parts Borax, 7 parts 

26 



sal ammoniac, lo parts ferrocyanide of potas- 
sium (prussiate of potash) and 5 parts rosin. 

Borax is also used for making finishing com- 
pounds for white fabrics, and for manufacturing 
gloss starch, stearine candles, colors, etc. 

FELDSPAR. 

Feldspar (K2 Ah Sic Oie and Na2 Ah S'u 
Oio), one of the most important ingredients of en- 
amel fluxes, is found in many different parts of 
the United States. When purchasing a supply 
of Feldspar, the manufacturer should, above all, 
try to obtain a pure white article, the smelting 
test being the simplest means of ascertaining 
whether it answers this requirement. 

When smelting pure, unmixed Feldspar, a 
transparent, distinctly crystalline mass of consid- 
erable hardness is obtained. 

The greater the purity of the Feldspar used, 
the purer will be the enamel. 

Manufacturers producing exclusively fine 
white enameled ware should buy their Feldspar 
in lumps and grind it in their own mills, this be- 
ing practically the only way in which they can 
be sure of always obtaining pure material, free 
from any foreign admixtures. 

Some manufacturers import their supplies of 

27 



Feldspar from Norway, which country produces 
the grade of Spar best adapted for making pure 
white enamel. The Norwegian article, however, 
may safely be replaced with the domestic product, 
as long as a pure white grade is obtainable. 

The answer to the question whether it is more 
advantageous to use Sodium Feldspar or Potas- 
sium Feldspar depends on the composition of the 
Enamel fluxes for which the material is to be 
used. 

QUARTZ. 

Quartz (Si O2) is a mineral of considerable 
importance both in enamel manufactiu'ing and in 
glassmaking. Either quartz or finely ground 
quartz sand or flint may be used, since all of 
these materials are chemically pure silex. If 
pure white quartz is obtainable, it should be used 
by preference for fine white Enamel, the price 
being, of course, generally too high to allow of 
the use of this material for all grades of Enamel, 
and more especially for colored enamels and glass 
fluxes. 

Quartz sand, deposited on the banks of large 
rivers, consists generally of Quartz rock, disin- 
tegrated by the powerful action of water, and it 
may be used as an excellent material for making 
Enamels and glass fluxes. 

28 



FLUORSPAR. 

Fluorspar (Ca F2) is a natural product, found 
in the form of beautiful crystals, or as a solid 
mass. In some places it occurs in an absolutely 
pure state, but colored Fluorspar in various 
shades is likewise found in many localities. 

Only absolutely colorless Fluorspar is available 
for Enamel manufacturing. It renders the En- 
amel more fluid, but great care must be used in 
employing Fluorspar as an admixture to Enamel, 
and more especially with Enamels used for the 
ground coat, the excess of lime having a detri- 
mental effect on their quality. 

SODA. 

Calcined Soda (Soda Ash, Na- COs) is the 
only kind used in Enameling Works, since the 
water contained in soda crystals is useless to the 
manufacturers and only increases the cost of 
transportation. 

An admixture of Soda and Potash in the right 
proportions gives Enamel a more brilliant gloss, 
while an excess of Soda makes it dull. Soda Ash 
contains 41% carbonic acid and 59% sodium. As 
common commercial Soda Ash generally contains 
considerable iron, which has. a very detrimental 

29 



effect on fine white enamel, and gives it a yellow- 
ish tint, the Soda manufactiu-ers have placed a 
special grade on the market, known as "Enamel- 
ing Soda," which is absolutely free from iron, but 
necessarily higher in price than the common 
article, for which reason it is. of course, used 
exclusively for fine white Enamels. 

Like Borax, Soda Ash must be stored in an 
absolutely dry place, for it will otherwise absorb 
moisture from the surrounding air and become 
caked into lumps as hard as rock. 

CRYOLITE. 

Cryolite (Noo AI2 Fil>) is a liux and further- 
more possesses in a very high degree the quality 
of making Enamel opaque. It occurs in nature 
in beautiful milky white pieces, greasy or oily 
to the touch, which can be easily scratched with 
the finger nails. It should be bought only in 
pieces, and manufacturers should not object to 
the trouble of grinding it, because they can only 
be sure of using an unadulterated material if 
they purchase it before it is ground. 

A new product, known as Artificial Cryolite, 
has recently been placed upon the market. It is 
a by-product obtained from the manufacture of 
artificial fertilizers, but it generally contains a 

30 



large percentage of silex and causes manufac- 
turers a great deal of trouble because it prevents 
them from making their Enamel opaque, while 
likewise impairing its fusibility. 

OXIDE OF TIN. 

Manufacturers have long been trying to dis- 
cover a substitute for the exceedingly expensive 
Oxide of Tin (stannic oxide, Sn O2) used in the 
preparation of Enamel. Many experiments have 
been made and some alleged substitutes were, in 
fact, placed upon the market, but as the results 
obtained with them were by no means satisfac- 
tory, consumers were compelled to return, al- 
though unwillingly, to the use of Tin Oxide. 

It is true that Oxide of Tin may partly be re- 
placed with White Oxide of Antimony, but the 
use of this latter product is likely to expose man- 
ufacturers to serious annoyances, inasmuch as 
the allegation might be made that their cooking- 
utensils are injurious to health, certain parties 
having claimed that inflammations of the blind 
gut are in a majority of cases due to the presence 
of poisonous enamel chips. 

It would, of course, be an exceedingly difficult 
matter for any one to prove this contention in the 
courts. I do not believe, in fact, that any one 

31 



engaged in the trade would refuse to perma- 
nently eat food cooked in utensils coated with 
Enamel containing antimony, inasmuch as the 
amount of antimony used is too small to have 
any injurious effect on the consumer's health. 

In this connection I consider it opportune to 
print below an expert opinion, issued by C. Sick, 
M. D., Physician in Chief of the 2d Surgical De- 
partment of the General Hospital ("Allgemeines 
Krankenhaus") of Hamburg-Eppendorf. 

Th;s authority writes: 

"The number of foreign substances found in 
the human intestinal tract is legion, and any of 
these substances may enter the vermiform appen- 
dix with the fecal matter when not too large. 
The fact, however, that such foreign substances 
are but rarely found in the appendix, suggests 
the possibility that the presence of a foreign 
substance will only cause morbid conditions when 
it either remains a long time in the appendix, or 
causes inflammations or lesions. Foreign sub- 
stances in the intestines are, however, invariably 
enveloped in fecal matter, and thus conveyed in a 
manner favorable to their excretion from the in- 
testinal canal. Investigations prove that even 
substances which, in view of their shape or form, 
might easily cause damage, such as fish bones, 

32 



needles and pins, pass rapidly through the in- 
testinal tract without causing any injury, be- 
cause the fecal matter which surrounds them 
makes them harmless. 

"In their attempt to discover the causes of ap- 
pendicitis, men of professional ability and mere 
meddlers have based their arguments on a great 
variety of theories which might possibly explain 
these causes. Among these attempts to explain 
the origin of the disease is the theory that ap- 
pendicitis is due to enamel chips from kitchen 
utensils, which find their way into the intestines 
and cause inflammation. 

"A perusal of the literature on the subject, 
which has assumed appalling proportions, shows, 
however, that no one ever really discovered an 
enamel chip in the vermiform appendix. And even 
though such a chip should actually be found in 
the appendix, such a discovery would still be de- 
void of all value as evidence, inasmuch as an 
enamel chip might just as easily be carried into 
the appendix, as fecal matter and other foreign 
substances have occasionally found their way 
there. 

"That the presence of an enamel chip in the 
vermiform appendix must be an exceedingly rare 
occurrence is proven by the fact that none have 

33 



ever been found (see Prof. Sprengel's opinion), 
as there is just as much chance of finding such 
a chip as of occasionally finding needles, fig- 
seeds or shot, all of which have been discovered 
in the appendix. It would first be necessary to 
prove that the presence of enamel chips in cases 
of appendicitis is a very frequent occurrence, and 
that there is any connection between their pres- 
ence and the morbid condition of the vermiform 
appendix, before it could be asserted that enamel 
chips are one of the causes of inflammation of 
the blind gut (caecum). 

"I have made investigations in Hamburg in 
both of the large General Hospitals, for the pur- 
pose of ascertaining whether an enamel chip had 
ever been found in the vermiform appendix in 
cases of appendicitis, or in any autopsy. The 
result proved that such had never been the case. 
In the General Hospital of Eppendorf I myself, 
with Dr. Kuemmell, removed the diseased vermi- 
form appendix by operation in more than i,6oo 
cases, without ever finding an enamel chip, not- 
withstanding our thorough examination. To 
this evidence should be added the numerous cases 
in which the same operation was performed in 
private practice, in which the search for such 
chips also produced negative results. According 

34 



to the report of Dr. Weininger, Surgeon in Chief 
of the St. George General Hospital, foreign sub- 
stances have been sought in all such operations. 
They were, however, discovered only rarely, 
those found being, for instance, pins, shot, apple 
and fig seeds, hairs from tooth brushes and in- 
testinal worms (Oxyures), but particles of tin 
from cans containing preserved food, as well as 
enamel chips, were never discovered in any of 
the cases. 

"Dr. Fraenkel and Dr. Simmones, Assistant 
Professors of Anatomy at the Anatomical Insti- 
tutes of the two General Hospitals, assured me 
in reply to an inquiry, that they had never found 
an enamel chip either in a case of appendicitis or 
in a sound vermiform appendix. 

"The foregoing facts, which are wholly in ac- 
cord with the findings of other investigators, lead 
to the conclusion that enamel chips have never 
been found in the vermiform appendix, and that 
they can consequently not be considered as the 
cause of any case of appendicitis. 

"The opinion that morbid conditions of the 
vermiform appendix are due to the presence of 
enamel chips from cooking utensils, which, un- 
fortunately, prevails quite generally, is based 
merely on a senseless repetition of a wholly un- 

35 



proven assertion which is unwarrantedly gaining 
wider circulation. 

''I am well aware, both from personal experi- 
ence and the statements of others, that cooked 
food sometimes contains enamel chips in the form 
of minute particles, scaled oft" from the cooking 
utensils, it being a well-known fact that this oc- 
casionally happens. These minute enamel chips, 
however, have as yet never been found in the in- 
testinal tract, or, more especially, in the vermi- 
form appendix, and no injury to health, or, to be 
more precise, no inflammation of the caecum 
(blind gut) was ever found to be attributable to 
the action of such enamel chips. 

"These enamel chips are heavy and will gener- 
ally fall to the bottom of the cooking utensils. 
If they enter the mouth with the food their pres- 
ence is readily discovered by the exceedingly high 
development of the sense of touch, because they 
are of irregular shape. They can then be easily 
removed, but even if they should accidentally en- 
ter the digestive tract, they pass through the 
same process as other foreign substances intro- 
duced into the human system with the food, i. e., 
they become imbedded in the contents of the in- 
testinal canal which form a thick mass when they 
reach the vicinity of the vermiform appendix. 

36 



and they are thus excreted with the fecal 
matter." 

This medical opinion clearly demonstrates that 
the assertions made in regard to the injurious 
action of enamel chips are untenable, and it is 
devoutly to be hoped that they may soon pass 
into oblivion. The report plainly demonstrates, 
in fact, that the assertion that inflammation of 
the blind gut is due to the presence of enamel 
chips in the intestinal tract rightly belongs to the 
realm of fiction. 

In continuation of my remarks concerning Ox- 
ide of Tin, I wish to point out that it is advisable 
to use this product very carefully, especially when 
it is intended for fine white enamel, inasmuch as 
some particles of tin are occasionally not com- 
pletely oxidized and the oxide consequently con- 
tains a percentage of metallic tin. 

The fired ware, or even utensils which have 
only received a coating of enamel, very fre- 
quently show black specks which indicate the 
presence of metallic tin. 

On observing the presence of these specks, a 
certain quantity of the Tin Oxide should at once 
be washed in water. The grayish granular pre- 
cipitate which is subsequently found on the bot- 
tom of the vessel consists of metallic tin. 

37 



In the up-to-date method of enamel prepara- 
tion, the Oxide of Tin is added exckisively when 
the other ingredients are in the grinding mill. 

COBALT. 

In olden times miners were apt to find in their 
ore workings heavy, glittering pieces of ore from 
which they hoped to obtain a large output of sil- 
ver. When treated in the smelting furnace these 
pieces would, however, soon disintegrate and 
form gray ashes, while generating a gas having 
a peculiar odor, similar to that of garlic, and the 
disgusted miners would consequently throw their 
disappointing pieces of ore away and called them 
"Kobolds," the old name of the malicious sprites 
which were supposed to be constantly fooling the 
miners. 

In our days, however, these pieces of ore are 
no longer neglected, but considered exceedingly 
valuable, because chemistry has discovered that 
these "Kobolds" contain a metal which enables 
us to impart an intensely blue color to glass 
fluxes. The modernized name of this metal is 
COBALT. 

The reason why this metal had not been found 
long ago in these deceptive pieces of ore is to be 
found in the different construction of the old 

38 



smelting furnaces which did not by any means 
generate the heat required for smelting Cobalt 
ores. 

By constantly keeping Cobalt at the glowing 
point while freely admitting atmospheric air it 
may be oxidized without melting the metal, the 
oxide being of a dark blue color. If Cobalt is 
kept at glowing heat during a still longer period, 
and subjected to a roasting process, it will absorb 
an additional volume of oxygen and is converted 
into the black oxide of Cobalt (CO.-? O4), which 
is a highly important factor in the enameling in- 
dustry. 

CLAY. 

Clay is one of the most important substances 
used in Enameling Works, and it is unfortunate 
that it generally fails to receive the careful at- 
tention it deserves. Many defects for which 
various alleged explanations are offered must, in 
fact, be attributed to the quality of the Clay. 

The grade of Clay best adapted for our pur- 
pose is the so-called "Vallendar"' Clay, found in 
the vicinity of Coblenz-on-the- Rhine (Ger- 
many ) . 

No matter what grades of Clay are used, they 
should always be soaked in pure water for a 

39 



period of 24 hours, before being used in the 
preparation of Enamel, inasmuch as the soaking 
process will remove from the Clay all the organic 
substances it contains. The process develops fer- 
mentation, which can be considerably hastened 
by the introduction of steam. The Clay is sub- 
sequently boiled for half an hour, by the end of 
which time all the gaseous fermentation products 
will have been carried off. 

After passing through the boiling process, the 
Clay is run through a fine screen, and the mass 
is then allowed to stand and the water which col- 
lects on the surface poured off. The Clay is then 
ready for being added to the enamel while it is 
in the grinding mill. 

A certain quantity of Clay, prepared as above 
described, should always be kept on hand. 

WATER. 

Necessity compels the manufacturer to be 
thoroughly acquainted with the quality of the 
water supplied to his works. The success he ob- 
tains with his products is largely dependent on a 
supply of water well adapted for the purpose for 
which it is used. 

In Enameling Works, rain water is unquestion- 
ably preferable to any other kind. 

40 



One or two large cisterns of sufficient capacity 
to supply the required amount of water are sunk 
into the ground and all the rain water that can 
be collected is run from the roofs into these cis- 
terns. A small pump, installed in the grinding- 
mill room, lifts the required amount of water 
from the cisterns and feeds it to the mills. 

If it is absolutely necessary to use water from 
the city or town water supply, which is generally 
very soft, it should be run into large vats, where 
a small amount of lime is added, and the water 
allowed to stand. As soon as the lime has settled 
on the bottom of the vats, the water can then be 
used for mixing with the Enamel in the grinding 
mill. 

Condensation water should never be used, no 
matter how pure it may be. 

Some manufacturers have installed water fil- 
tering plants in their works, animal coal filters 
being most suitable for our purposes because they 
w^ll retain all solid substances, but as all filtering 
processes involve a considerable expense, we 
would urgently advise manufacturers to collect 
the rain water, as above described. 

Before entering upon a description of the en- 
ameling process proper, I shall proceed to insert 
for the benefit of my readers a number of reliable 

41 



formulas for the preparation of Enamel. In se- 
lecting these formulas, the author's principal con- 
sideration has been to publish in this volume, as 
a guide for his readers, only such as he has per- 
sonally and practically tested. Any manufac- 
turer may, moreover, use any of the following- 
formulas, without any further preparation, for 
making his enamels in accordance with the direc- 
tions given in this Manual. 

GROUND COAT NO. i. 



IvBS. OZ 

Feldspar 60 

Quartz 52 

Borax 80 

Soda Ash 20 

Fluorspar 8 

Calcspar 8 

Saltpeter 8 

Oxide of Cobalt 

Oxide of Manganese 14 

When charging the ]\Iill add 9% Clay. 

42 



/ 



GROUND COAT NO. 2. 

LBS. OZ 

Feldspar 56 

Quartz 40 

Borax 60 

Soda ash 20 

Saltpeter 9 

Fluorspar 12 

Oxide of Manganese 2 

Oxide of Cobalt } 

When charging- the JMill, add 10% of Clay. 

GROUND COAT NO. 3. 

LBS. OZ 

Feldspar 51 

Quartz 82 

Borax 86 

Soda Ash 18 

Saltpeter 18 

Calcspar 22i 

Fluorspar 20 

Oxide of Cobalt 4 

Oxide of Manganese 2 

When charging the Mill, add 6% Clay, and 1% 
Borax, dissolved in W^ater. 

43 



GROUND COAT NO. 4. 
vis: A. 

LBS. oz 

Feldspar 84 

Quartz 58 

Borax 92 

Soda AshK%. P:,} 26 

Saltpeter .'"^(j. 16 

Fluorspar 12 

Oxide of Cobalt. CMi^/^.^ 13 

Oxide of Manganese ... (.< t"j 7 

vis: B. 

LBS. oz. 

Feldspar 128 

Quartz 16 

Borax 108 

Soda Ash 12 

Saltpeter 9 

Fluorspar 26 

Magnesia Carbonate . '| vv^^. 2 

Oxide of Cobalt 13 

Oxide of Manganese 7 

When charging the Mill, take 1/3 of vis: A. 
and 2/3 vis: B., also 9% Vallendar Clay, 10% 
ground Glass, and 1% Borax dissolved. 

44 



DARK BLUE. 

LBS. OZ. 

Feldspar 120 

Quartz 'J2 

Borax 80 

Cryolite 30 

Saltpeter 7 

Oxide of Cobalt 7 8 

Oxide of Manganese i 

When charging the Mill, add 4% white Clay. 
BLACK. 

LBS. OZ. 

Feldspar 35 

Quartz 60 

Borax 75 

Soda Ash 27 

Fluorspar 15 

Saltpeter 12 8 

Oxide of Manganese 15 

Oxide of Cobalt 2 8 

Black Oxide of Copper 3 

When charging the Mill, add 9% Clay. 

45 



WHITE NO. I. 

LBS. OZ 

Feldspar 55 

Quartz 24 

Borax 24 

Cryolite 18 

Soda Ash 8 

Fluorspar 5 

Clay 6 

Saltpeter 5 8 

When charging the Mill, add 9% Vallendar 
Clay, and 10% Oxide of Tin. 

WHITE NO. 2. 

LBS. OZ. 

Feldspar 67 

Quartz 90 

Borax 45 

Soda Ash 18 

Boracic Acid 20 8 

Saltpeter 9 

Cryolite 41 

Fluorspar 9 

When charging the ]\Iill, add 12% Vallendar 
Clay, 12^^ Oxide of Tin, 1% Soda Ash. 

46 



WHITE NO. 3. 

LBS. OZ. 

Feldspar 76 

Quartz 48 

Borax 46 

Soda Ash 10 

Cryolite 23 

Saltpeter 7 

When charging the Mill, add 10% of Vallendar 
Clay and 10% Oxide of Tin. 

WHITE NO. 4. 
White Powder Enamel for Signs. 

LBS. OZ. 

Boracic Acid 12 

Quartz 40 

Cryolite 18 

Red Lead 14 

Soda Ash 2 8 

Saltpeter i 4 

When charging the JMill, add 10% Oxide of 
Tin; after milling dry it, and use a 90-Mesh 
Screen for powdering. 

47 



EDGING BLUE. 

LBS. OZ 

Feldspar 64 

Qwartz 54 

Borax 90 

Soda Ash 23 

Fluorspar 16 

Saltpeter ii 

Oxide of Cobalt 5 

Oxide of Manganese 2 

This Enamel must be smelted twice, and when 
charging the Mill, add 6% white Clay. 

EDGING BLACK. 

I.BS. OZ. 

Feldspar 36 

Quartz 36 

Borax 80 

Soda Ash 18 

Fluorspar 12 

Saltpeter 10 

Oxide of Manganese 8 

Oxide of Cobalt i 12 

Oxide of Copper i 12 

Oxide of Nickel i 8 

When charging the Mill, add 5% brown Clay. 
48 



COPPER BROWN. 

LBS. OZ 

Feldspar 50 

Quartz 15 

Borax 21 

Soda Ash 15 

Fluorspar 6 

Saltpeter 3 

Cryolite 2 

Red Oxide of Iron 12 

When charging the Mill, add 5% Clay, and 4% 
Red Oxide of Iron. 



GREEN. 

IvBS. OZ 

Feldspar 30 

Quartz 52 

Borax 65 

Soda Ash 20 

Saltpeter 12 

Fluorspar 15 

Black Oxide of Copper 12 

When charging the Mill, add 3% white Clay. 



All of the foresfoino- formulas are exclusively 
for enameling sheet-steel ware, and I am con- 
vinced that any one engaged in this line of manu- 
facture will be able to prepare on the basis of my 

49 



said formulas any kind of Enamel required in the 
production of enameled sheet-steel ware. 

For making other colored Enamels, the only 
thing- required is a flux, to which the coloring 
substances, which can be readily purchased in any 
form desired, are added in the mill, to be ground 
with the ingredients for the flux. 

During the past ten years the manufacture of 
enameled signs has grown to enormous propor- 
tions, chiefly on account of their durability, 
weatherproof qualities and artistic design. 

In this manufacturing line the ordinary wet 
enamel is used for large signs, while it is advis- 
able to use powdered enamel for small-sized signs. 
The following formulas will be found very useful 
for preparing various powdered enamels, 

WHITE NO. I. 

LBS. OZ. 

Feldspar 39 

Quartz 64 8 

Boracic Acid 18 

Cryolite 4 

Potash 9 

Soda Ash 6 

Red Lead 36 

Oxide of Antimony, White 16 

50 



WHITE NO. 2. 

LBS. OZ. 

Feldspar 37 

Quartz 56 

Boracic Acid 15 8 

Cryolite 6 

Potash 9 

Soda Ash 4 

Red Lead 28 8 

Oxide of Antimony, White 14 

YELLOW. 

LBS. OZ. 

Feldspar 15 

Quartz 23 

Sand 35 

Boracic Acid 48 

Cryolite 23 

Red Lead 160 

Saltpeter i 6 

Magnesia Carbonate 10 

Soda Ash 14 

Oxide of Tin 20 

Oxide of Antimony 21 

51 



RED. 

LBS. OZ. 

Feldspar 12 

Quartz 5 6 

Boracic Acid 8 

Red Lead 14 

Cryolite 2 

Soda Ash 4 

Potash 4 

Oxide of Tin 2 

Red Oxide of Iron 3 8 

Magnesia Carbonate 2 

BROWN. 

LBS. OZ. 

Feldspar 22 

Quartz 27 8 

Boracic Acid 55 

Cryolite 12 

Red Lead 100 

Saltpeter 6 

Soda Ash 12 

Red Oxide of Iron 8 8 

52 



BLUE. 

LBS. OZ 

Feldspar 23 

Quartz 24 

Boracic Acid 27 

Red Lead 11 

Cryolite 3 

Soda Ash 11 

Bone Ash 4 

Potash II 

Oxide of Cobalt 2 12 



However, as stated before, poorly mixed 
ingredients cannot produce a homogeneous 
enamel, and if small amounts of a poorly made 
mixture are charged into the smelting furnace 
it becomes impossible for the various ingredients 
to partly remedy during the smelting process the 
lack of homogeneity due to inadequate mixing. 

It is consequently absolutely necessary that all 
the ingredients that have been weighed and mixed 
be charged in one batch into the smelting furnace. 

If a manufacturer makes, for instance, a mix- 
ture weighing 1,000 pounds, and smelts the same 
in two batches of 500 pounds each, then the com- 

53 



position of each batch would not be in conformity 
with the original formula, and the use of the 
enamel produced with the same would result in 
the production of defective goods. 



54 



The Smelting Process 

From the mixing-room the enamel composition 
is conveyed to the smelting furnaces, which are 
generally vat furnaces, burning coal, oil or gas. 
It is of the utmost importance to have the 
smelting furnaces, and particularly the furnace 
bottoms, sufficiently heated before putting in the 
charge of Enamel, as it is evident that the top of 
the mass is exposed to the greatest heat, while 
the only heat it receives from the bottom is that 
which has been stored up by previously heating 
the empty vat. It is true that the heat will 
naturally be conducted from the top to the bottom, 
but the upper part of the mass, nevertheless, 
receives more heat than the lower part. 

After a charge has been taken from the fur- 
nace, the latter should always remain empty for 
a short time, in order to store up a sufficient 
amount of heat in the bottom. 

It is exceedingly advisable to have the mass 
stirred up or raked over at short intervals while 
in the furnace, in order to equalize the uneven 

55 



heating. In this connection it is well to bear in 
mind that the Enamel will be all the more homo- 
geneous if each layer of the mass receives an 
ec|ual amomit of heat. 

This stirring or raking over is, in fact, one of 
the factors which determine the result. During 
the smelting process the ingredients of the mass 
will at first separate to a certain extent. The 
substances which have a low fusing point will 
fuse first, while those which have a high fusing 
point have a tendency to settle down to the 
bottom of the furnace. 

In case of failure to frequently and thoroughly 
rake over the mass while it is in the furnace, the 
silicates will not, therefore, be rendered evenly 
soluble, and the enamel will consequently be of 
inferior quality. 

The man whose duty it is to charge and dis- 
charge the furnaces knows exactly when the time 
for running off has arrived. He can observe the 
interior of the muffle through the peep holes, and 
as soon as all ebullition ceases and the mass 
remains as smooth as a mirror after having been 
stirred up for the last time, the charge is ready 
for tapping. 

After the furnace tender has opened the door 
the Enamel is run off into a large tank filled with 

56 



cold water, and breaks up into small particles, in 
consequence of the sudden chill. 

Only a reliable workman can, of course, be 
employed for conducting the smelting operation, 
as every man conversant with the trade knows 
the annoyances and disappointments resulting 
from the use of Enamel that has either not been 
smelted to a finish or been burnt in the smeltins:. 



5: 



The Grinding Process 

From the smelting furnace the Enamel is con- 
veyed to the grinding room, which must be the 
cleanest room in the works, and is to be kept free 
from every particle of dust. 

At the present time Enamel is exclusively 
ground in pebble mills, lined on the inside with 
hard porcelain bricks. When once these mills are 
charged and in operation they require compar- 
atively little power. 

For grinding very fine enamels it is advisable 
to use the French pebble mills or else mills with 
drum and balls of hard porcelain, because the 
use of these mills makes it absolutely impossible 
for any particles of cement or iron to become 
mixed with the Enamel during the grinding. 

The pebble mills must be carefully inspected 
at intervals to ascertain whether the porcelain 
bricks have worn out. If so, the mill must be 
provided with a new lining. 

In the grinding room the Enamel is weighed 
out in batches corresponding to the capacity of 

58 



the mill and charged into the mill with a propor- 
tional amount of pure, clear water. 

Inasmuch as water alone will not thoroughly 
combine with Enamel, a certain percentage of 
clay, figured on the basis of the weight of the 
Enamel, must be added to each batch of the 
latter. 

This admixture of clay serves the purpose of 
keeping the ground Enamel suspended in the 
liquid and prevents it from settling on the bottom. 

The preparation of the clay has been described 
in a previous chapter (see chapter "Clay"). 

In order to make white Enamel absolutely 
white and thoroughly opaque, a percentage of 
oxide of tin, figured according to the quality of 
the Enamel, must be added when the latter is in 
the mill. 

Some works are following the reprehensible 
practice of running ofif the Enamel from the mill 
into high, narrow barrels as soon as it has been 
sufficiently ground. This method should never 
be used under any circumstances, because heat is 
frequently generated in the mill by friction 
between the small round pebbles and the Enamel, 
which makes it necessary to run ofif the finished 
Enamel into large, flat tanks, lined with zinc, 
where it can cool at once. 

59 



When the Enamel is run off into barrels, as 
aforesaid, it will retain its heat for a considerable 
time, and when such Enamel is used for the sheet- 
iron ware it will become dull during the firing 
process, inasmuch as the Enamel has become 
devitrified by being allowed to retain its heat 
too long. 

Before using the ground Enamels for coating 
the utensils they must be tested for their density. 
Should they prove to be too thin they must be 
slightly thickened or given the right body. This 
is accomplished by adding a solution of sal 
ammoniac, common salt, magnesia, Epsom salts 
or borax, drop by drop, to the Enamel. In this 
connection it appears advisable to state that the 
thickening should never be entrusted to the men 
who are employed in coating the ware, because 
they will always give the Enamel the body wdiich 
makes their work, i. e., the coating, easiest. 

When Enamels are ground very fine they will 
have a more brilliant gloss than coarsely ground 
Enamels, but they should, nevertheless, not be 
ground too fine, as they are liable to become 
viscid and produce a streaky coating, from which 
even the most skilful coater cannot remove the 
streaks. 

About 1% red oxide of iron should be added 

60 



to dark blue Enamel, as it gives it a richer 
coloring. 

For making all other kinds of colored Enamel 
it is generally sufficient to use a glazing, to which 
the various coloring materials are added while in 
the mill. The amount of oxide of tin or cryolite 
to be added to the mass depends on whether the 
Enamels are to be light or dark colored. If very 
dark shades are to be produced the oxide of tin 
and cryolite are entirely omitted, while at the 
same time adding a correspondingly larger 
amount of coloring matter. 



61 



The Coating and Firing 
Processes 

After the crude ware has been pickled and the 
dents, if any, have been beaten out, it is conveyed 
to the enameHng or coating room proper. In 
this room pans of adequate size for holding the 
utensils are imbedded in the tables, the rims of 
the pans being level with the table top. Behind 
each pan is placed a large screen, the lower part 
of which points in the direction of the pan. 
These screens serve the purpose of catching up 
at once the Enamel which is squirted in a forward 
direction and of conveying it back into the coating- 
pan. 

The pans and screens must have a ground coat 
of Enamel, so as to prevent rust or iron from 
becoming mixed with the coating Enamel. 

A further requirement is a number of shelves, 
adjusted to the height of the utensils which are 
left to dry on these shelves. The furnace flues 
are generally made to pass under the shelves, so 

62 



as to utilize the heat of the flames while they are 
carried off. 

The first coating which the crude ware receives 
is a coat of ground coat enamel. 

The essential quality of ground coat enamel is 
that it has a comparatively low fusing point. It 
contains either an admixture of oxide of cobalt 
or of oxide of nickel and manganese. 

These metallic oxides, in conjunction with 
borax, impart to the Enamel a coefficient of 
expansion which is approximately the same as 
that of sheet steel. 

Ground coat enamels to which only oxide of 
nickel has been added (known as nickel ground 
coat enamels) require a great deal of care and 
attention during the coating and firing processes, 
and they are not as durable and elastic as cobalt 
ground coat enamel. 

Ground coat enamel must not be ground too 
fine, and the coating must be rather thin. When 
a ground coat is put on too thick it is liable to 
scale off and to produce the exceedingly annoying 
minute cracks or chinks. Care should also be 
taken to put on a thin coat under the rims and 
over the seams, as blisters are otherwise liable to 
appear in these places. 

It is essential to dry the ware quickly after 

63 



the ground coat has been put on, in order to 
prevent rusting under the enamel. Recourse is 
also frequently had to a slight addition of borax 
solution for the purpose of preventing rust stains. 
After the ground coat has been put on and 
dried, the ware should not be passed on to the 
kiln before it has been inspected for the purpose 
of ascertaining whether there are any spots in 
which the metallic surface can be seen through 
the enamel. If so, these spots must be coated 
over, inasmuch as the metal in these places would 
otherwise be converted during the firing process 
into black oxide of iron, to which the subsequent 
coating of white enamel will not adhere. All the 
ware fired without recoating these spots would 
consequently be either seconds or refuse. 

We have for a long time past been trying to 
make a white ground coat enamel without an 
addition of the oxides of cobalt or nickel, and 
numerous experiments have been made, regard- 
less of expense. All efforts, however, proved to 
be in vain, and all technical men in the enameling 
trade now concur in the opinion that any further 
attempts to produce such an enamel would merely 
be a waste of time. 

After the ground coat has been fired on the 
ware, a process which requires a very high 

64 



temperature, in order to convert the large per- 
centage of borax contained in the enamel into 
a thin liquid which will enter into a close combi- 
nation with the sheet steel, the ware is subjected 
to the second operation, viz., that of receiving its 
first coat of white enamel, which should be com- 
paratively thin. 

In order to produce very handsome ware it is 
advisable to put on the blue or black rim when 
the ware has received its first white enamel coat. 
This putting on of the rims should be done very 
carefully, as a fine, clean rim will give the ware 
an attractive appearance. 

There are different methods of putting the rim 
on the ware, and their selection will largely 
depend on the question whether the enameling 
foreman has been accustomed to one or the other 
of these methods, i. e., whether he has put them 
on by hand or on a glass or steel plate. The 
latter method is preferable, because it produces 
a cleaner and more even rim. 

After drying the first coating of white enamel, 
which should, if possible, be done without using 
the heat from the furnace flues, and merely by 
the atmospheric air, the ware is again passed on 
to the kiln and fired at low heat. 

After this operation the ware is given its 

65 



second and last coating of white enamel, which 
is intended to give the goods an attractive appear- 
ance, and should consequently be carefully put 
on, without streaks. 

It is one of the duties of the foreman of the 
enameling shop to construct such tools for coating 
and firing as will protect the ware from being- 
bent out of shape, so as to avoid, as far as 
possible, the necessity of straightening out the 
utensils after the firing operation. Straightening 
out is, in fact, liable to injure the rims, as they 
will in certain places scale off and leave the iron 
surface exposed, a defect which means more 
seconds and refuse. 

It is, moreover, exceedingly important to have 
the unfinished ware which is to be enameled most 
carefully made in every respect. The folded 
seams and the riveting should be solid, the rims 
either tightly closed or entirely open, and in 
making stamped ware special care should be 
taken to give the bottom the proper tension, as 
the enamel will frequently scale off, during the 
heating, in the middle of the bottom, owing to 
the uneven tension, a defect which means no end 
of annoyances for the manufacturer. 

This defect, however, can be easily remedied 
by stamping an embossed ornament, or better still, 

66 



the trademark, in the middle of the bottom, 
where it will take up all the surplus material, 
thereby leaving the bottom free to warp in both 
directions. 

There are too many possible manufacturing 
defects, and too many possible causes for the 
same, to discuss them all in this volume. I shall, 
however, enumerate a few of the defects which 
are of most frequent occurrence, stating at the 
same time their possible causes, hoping to thus 
assist many manufacturers in discovering the 
mistakes to which such manufacturing defects as 
they may have observed in their product are to 
be attributed. 

1. Scaling off of the enamel on the bottom and 
at the rims. 

Possible Causes: Uneven tension in the bot- 
tom. The use of too hard enamel on the rims. 
Too much annealing. Ground coat enamel fired 
at too low a heat. Moisture in the rolled rims. 

2. Blisters forming streaks on certain parts of 
the utensils. 

Possible Causes: Too thick a coating of ground 
coat enamel. The ground coat enamel does not 
properly correspond with the covering enamel. 
The presence of too large a percentage of 
fluorspar in the enamel. Firing at too low a heat. 

67 



3- Blisters irregularly distributed and of 
irregular size. 

Possible Causes: Insufficiently smelted enamel. 
The use of clay containing organic matter. Ware 
insufficiently annealed and pickled. 

4. White specks in colored enamel. 

Cause: The ware was placed with moist hands 
on the firing bars. 

5. Disappearance of the gloss. 

Possible Causes: An inflow of gases through 
the leaky walls of the muffle while the furnace 
was charged. Devitrification due to repeated 
firing. 

All of the aforesaid defects demonstrate that 
absolute cleanliness is a necessary requirement 
in all stages of the enameling process. 

The well-known muffle furnaces of various 
types of construction, burning coal, oil or gas, are 
used as kilns for firing the enamel. 

Furnaces without muffles are in operation in a 
few works, but their use cannot be recommended, 
because the fire must be turned ofif each time 
they are charged, such furnaces being conse- 
quently never evenly heated while the charge is 
put in. Moreover, there is frequently an accumu- 
lation of gases which have a most injurious effect 
on the articles to be fired. 

68 



In this connection we would add that it is 
advisable to provide reliable pyrometers for veri- 
fying the proper temperature both in muffle and 
smelting furnaces, inasmuch as the use of Seger 
cones does not only take a good deal of time, but 
is also very expensive. 



69 



The Coefficients of Expan- 
sion of Sheet-Steel 
Enamels 

Some exceedingly valuable and interesting tests 
have been made at the Polytechnic of Karlsruhe 
(Germany) in regard to the coefficients of expan- 
sion of sheet-steel enamel and of various grades 
of sheet steel. The report concerning these tests 
reads as follows: 

"By direct determination of the coefficients of 
expansion according to the Fuers method, we 
were able to prove that the assumption that 
ground coat enamels served the purpose of equal- 
izing the difference in expansion between the 
covering enamel and the steel is not based on fact, 
inasmuch as the coefficient of expansion of 
ground coat enamels is even slightly lower than 
that of coating enamels. Changes in the amount 
of borax added to the enamel do not materially 
alter its expansion capacity. The coefficient of 
expansion of the various grades of sheet steel 

70 



were found to be from 20% to 30% higher than 
those of any of the enamels tested. The coefficient 
of expansion of steel decreases by ^7^ by coating 
with ground coat enamel, and by 10% by coating 
with both ground coat and covering enamel. 
There are consequentl}^ very high tensions in 
enameled utensils, and this furnishes an explana- 
tion of the fact that enameled ware will very 
frequently crack and split without any external 
cause." 



71 



Cast-iron Enameling 

Enamels for cast-iron ware require entirely 
different treatment and are of different composi- 
tion than sheet-steel enamels. 

Utensils for cooking and chemical purposes 
are known in the trade as "cast pottery." 

Only fritted ground coat compositions are 
used for ware of this kind. The trade term 
"fritted" applies to such mixtures as have only 
been brought to the slagging point. 

These frit mixtures are charged into the muffle 
furnace in a flat pan, lined with clay, and left in 
the furnace until they are converted into a 
porous, spongy mass. 

After passing through this slagging process 
the mass is ground in a wet mill w4th admixtures 
of clay, feldspar, quartz, etc. 

I give below a few formulas for ground coat 

frit: 

FRIT NO. I. 

LBS. OZ. 

Sand 36 

Borax 9 

72 



When charging the mill, add 30% quartz and 
10% clay. 

FRIT NO. 2. 

LBS. OZ. 

Sand 44 

Borax 19 

Saltpeter 14 

When charging the mill, add 9% quartz and 
12% clay. 

FRIT NO. 3. 

LBS. OZ. 

Sand 36 

Borax 15 

Carbonate of Magnesia i 2 

When charging the mill, add 25% clay. To 
hold up, use soda phosphate. 

WHITE FOR POTTERY. 

LBS. OZ 

Feldspar 39 

Sand 30 

Borax 30 

Soda Ash 24 

Fluorspar 9 

Whitening 4 8 

Oxide of Zinc 6 

When charging the mill, add 14/^ oxide of tin, 
7% oxide of zinc, 7% clay. 

71 



The sand blast provides a very efficient means 
for cleaning cast-iron ware. Acids of any kind 
should never be used for this purpose. 

After the cast ware has been cleaned a thin 
ground coat is put on, dried and fired at red heat. 
After firing, the ground coat must have a rough 
surface and no gloss. 

After cooling the ware thoroughly the ground 
coat is moistened with a sponge and the white 
enamel first thoroughly rubbed in with a brush, 
so as to fill all the pores of the ground coat. The 
white enamel is thereupon poured over every 
part of the utensils, which are subsequently 
struck lightly with a wooden hammer in order 
to make the enamel run off evenly. 

It is absolutely necessary to cool the fired cast- 
iron ware slowly. 

Large-sized articles are enameled by the dry 
method, for which powdered enamel is used. 
This is spread through a sieve over the metal 
surface of the utensils, while they are at red heat, 
and without any ground coat. 



74 



Majolica Ware Enamels 



The production of enameled ware in imitation 
of Majolica ware is no longer a difficult matter. 
Art castings, such as high-grade gas stoves, gas 
ranges, etc., made in ornamental style, are 
exceedingly well adapted for this kind of 
enameling. 

When fired at a high temperature Majolica 
ware enamel will flow into the recesses of the 
casting and leaves only a slight gloss on the 
protruding parts. The recesses will consequently 
be of a darker shade than the protruding parts, 
and the casting will thus have the appearance of 
Majolica ware. 

Articles to be enameled in imitation of Majol- 
ica must first receive a ground coat, and subse- 
quently, after firing, a coat of white enamel, 
whereupon they are subjected to a second firing- 
process. When thus prepared the colored enamel 
wall stand out splendidly on the white ground. 

It is not absolutely necessary to use a special 
kind of ground coat enamel, as the ordinary 
ground coat enamel for cast pottery will answer 
the purpose. 

75 



WHITE GROUND COAT FOR MAJOLICA 
WARE IMITATION. 

LBS. OZ. 

Feldspar 15 

Quartz 12 

Boracic Acid 7 8 

Soda Ash 4 8 

Red Lead 3 8 

Whitening 3 8 

Oxide of Zinc I 8 

Oxide of Antimony I 4 

Saltpeter i 6 

FLUX FOR MAJOLICA COLORS. 

LBS. OZ. 

Feldspar 10 

Quartz 22 

Borax 12 

Red Lead 62 

Soda Ash 6 

Saltpeter 2 8 

Oxide of Tin 3 8 

The various coloring matters are added in the 
mill, according to the shade desired. 

It is advisable to smelt all enamels intended 
for Majolica imitation in the crucible, and to 

76 



smelt them twice. After the first smelting the 
contents of the crucible should be allowed to drip 
out into a dry receptacle, and after the second 
smelting into a pan filled with pure water. 

The grinding process is conducted in the same 
manner as for any other enamels, in a pebble mill 
with porcelain balls, but care should be taken to 
grind all enamels intended for this purpose 
exceptionally fine. It is absolutely necessary to 
keep Majolica glazings made by this method in 
tightly closed containers until they are used. 



in 



Enamel Painting 

After placing their white utensils, resembling 
chinaware, upon the market, the Enameling 
Works were soon compelled to avail themselves, 
as far as possible, of the art of enamel painting 
and to delve into its secrets, so as to impart to 
their enameled utensils the closest possible 
resemblance to the products of the chinaware 
industry. 

Those who have an opportunity to inspect the 
finely decorated enameled ware exhibited at the 
present time by importing firms in New York 
and other cities cannot fail to marvel at the 
diversity of designs and at the splendid efifect of 
the artistic decorations which embellish these 
articles. 

Enamel painting and china painting are two 
closely related professions, although not wholly 
similar. The principal difference consists in the 
composition of the smelting fluxes. 

These fluxes, mostly lead fluxes, are added in 
varying proportions to the colors which are com- 

78 



posed of a series of metallic oxides, for the pur- 
pose of obtaining the desired firing point. The 
painter must be thoroughly conversant with the 
fusing point of his colors and he must always 
select the proper flux for each color, because 
some colors will stand more heat than others. 

Hand painting is principally used for special 
utensils or ware, such as trays, tea and coffee 
urns and fine wash-bowls and pitchers. 

As hand painting, however, is very expensive, 
manufacturers are at the present time using 
various substitutes which reduce considerably the 
cost price of decorated ware. 

One of these substitutes is, for instance, steel 
plate printing, a method by which the finest 
shading can be obtained, leaving nothing to do for 
the painter except to glaze them over with the 
proper colors. 

The sketching of the decorative designs on the 
steel plates requires, of course, great artistic 
ability and intelligence. 

The engraved plates are placed upon a heating 
plate, heated either by gas or electricity, and kept 
at moderate heat. The painter then covers the 
steel plate with his thickly mixed color, which 
must be of a rather tough consistency, and 
removes the color from all the parts of the steel 

79 



plate which are not engraved by firmly rubbing 
a piece of stiff paper over the entire surface of 
the plate. The thin printing paper especially 
prepared for this purpose is moistened, spread 
upon the steel plate, both being thereupon passed 
through a printing press which imprints the sharp 
outlines on the thin printing paper. 

When the paper has thus been printed it is 
laid with the printed side on the ware which is 
to be decorated, pressed down with a moist 
sponge and all the folds are smoothed down with 
a hard rubber roller. The paper is thereupon 
carefully lifted off, when the outlines of the 
design will appear transferred on the article or 
utensil. 

The painter now fills in the design with the 
proper colors and the piece thus decorated is 
ready for firing. 

Enamel colors are generally so prepared that 
they will flow very readily, and firing requires the 
closest attention and the greatest care. 

The so-called ''air-brush work" is another 
method, and fairly attractive decorations can be 
obtained with the same with the aid of stencil 
patterns. 

The cheapest method of decorating enameled 

80 



ware, however, is unquestionably the use of 
ceramic transfer or decalcomania pictures. 

These transfer pictures are made by manufac- 
turers who make a specialty of this line. They 
are manufactured by chromo-lithography, with 
the use of enamel colors and a collodion coating. 

For transferring these ceramic decalcomania 
pictures properly they are placed for a few 
minutes in lukewarm water. After making sure 
that the collodion film has been dissolved, the 
pictures are spread on the articles which are to 
be decorated and the backing carefully drawn off. 
The pictures are then pressed closely against the 
outside of the article, conforming to its shape, 
and smoothed down as perfectly as possible by 
slight pressure with a sponge. 

When this has been done there will still remain 
a few small blisters formed by water or air, and 
these are carefully rolled down and smoothed out 
with a rubber roller. 

The latter work must be very carefully done, 
as the small blisters would otherwise burst in the 
furnace, thereby spoiling the entire picture. 

After this operation the articles to which the 
pictures have been transferred are charged into 
a dryer, where they must be dried hard before 
they are conveyed to the kiln or furnace. 

81 



Moist pictures would either become entirely 
detached from the ware while in the kiln, or else 
they would be torn to pieces. 

Decorated with the picture alone, the ware 
would have an imperfect appearance. In order 
to improve it the rims, handles, etc., are striped 
by the painter either in gold or some other color, 
the ware being thereupon charged into the firing 
furnace, in which it must be fired only once. 

The manufacturers of transfer pictures are 
now making splendid goods which enable the 
mantifacturer to decorate his product at a very 
small cost. 



82 



Pastel Painting on Enam- 
eled Paints 

Pastel painting on enamel is an entirely new 
invention, principally used in art painting for 
producing portraits on enameled plaques, because 
such portraits will remain unchanged during 
many generations. Any fading of the colors on 
an enameled plaque would be absolutely impos- 
sible, as the colors are baked at a high temper- 
ature, and such pictures need not, therefore, be 
framed under glass. Dust and other impurities 
can readily be removed by rubbing with a cloth 
moistened with alcohol. 

The technique of enamel painting is exceed- 
ingly complicated, and the application of the 
colors on the smooth surface of the enameled 
plaque by means of colored crayons requires both 
a peculiar faculty and artistic talent on the part 
of the painter. 

Enamel plaques intended for portrait painting 
must be prepared as follows : 

First of all, the white enamel used for this pur- 

83 



pose must be made of the very best materials and 
ground very fine, so as to obtain a fine grain. It 
must, moreover, be applied with the utmost care, 
to avoid all streaks and lumps. 

After the enamel has dried on the plaque it is 
fired lightly in the muffle furnace. When taken 
out the surface must be rough, without gloss, 
because the color from the crayons would not 
otherwise adhere to it. 

The colored crayons must be made of a certain 
degree of hardness so they will yield enough color 
for providing very dark shades whenever 
required. 

After the drawing of the picture has been 
completed the plaque goes to the furnace, where 
it is fired to a finish, and thereby acquires the 
necessary gloss. 



84 



Pastel Crayons 

The painter entrusted with making the crayons 
must have a thorough knowledge of the colors he 
intends to use, and be perfectly familiar with 
their action when baked at a high temperature, 
if he is to produce a perfect picture. 

The mass used for making pastel crayons is 
prepared and treated as follows: The color is 
mixed with a watery solution of gum arable and 
thoroughly kneaded until a solid mass is obtained 
which will not change its form after having been 
allowed to stand for some considerable time. 

After making sure that the mass is of solid 
consistency, it is divided up into small equal parts, 
each of which must be sufficient for making one 
crayon. The parts are then rolled into a cylin- 
drical shape of the desired thickness and cut 
down to a convenient length, usually ranging 
between 5 and 6 inches. 

The crayons must be thoroughly air dried and 
pointed with a sharp file. They are then ready 
for the painter. 

85 



Only an experienced and intelligent porcelain 
and enamel painter should, of course, be entrusted 
with the preparation of the pastel crayons, as the 
composition of the colors is wholly different from 
that of ordinary water colors. 

A common paper stump is used for rubbing 
down the colors. 

This pastel painting method is undoubtedly 
destined to have a great future and will appeal 
most favorably to lovers of art. 



86 



The Application of Photo- 
Ceramics to Enamel 

The production of photographs on enamel 
plaques has during the past few years developed 
into an independent branch of industry. 

Photographs on enamel plaques can be made 
without any serious difficulty, the method most 
generally used being the dusting process. This 
method is based on the known phenomenon that 
a mixture of acid potassium chromate, gum, 
albumen and gelatine will become insoluble under 
the influence of sun rays. 

The process is as follows : 

A mirror plate is coated with the above 
described mixture and dried. When dry the plate 
is exposed to the light under a positive, which can 
be obtained from the photographer after he has 
taken a picture. After the plate has been suf- 
ficiently exposed to the light, the Enamel color is 
carefully dusted on. As the color will not adhere 
to the parts of the plate which were exposed to 

87 



the light, the dusting has made the picture visible. 
It is thereupon coated with collodion and treated 
with alkaline water, in order to dissolve the chro- 
mium compounds and transfer them with the col- 
lodion film to the enamel plaque. The collodion 
is finally removed by dissolving it and the picture 
is then ready prepared for firing. 

The above described process was invented by 
two Frenchmen, Messrs. Salmon and Garnier. 




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THE 



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Chemical Company 



MAIN OFFICE : 

100 William Street 

New York 

FACTORY : 

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BRANCHES : 
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FOUNDED 1869 



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